120 



Ips englemanni Sw.; Dom. Ent. Br., Dept. Agric, Bull. 14: 30, 1917. 



This species agrees with tridens in all characters of the pronotum and 

 elytra; it differs only in the nature of the frontal tumulus, which is much 

 less elevated, with its cephalic face densely clothed with very long, incurved, 

 light yellow hairs. Ips pilifrons Sw. is entirely distinct from engelmanni in 

 its larger size, with the strial punctures very coarse, close and usually 

 quadrate, the frontal tumulus still less elevated, with its cephalic face more 

 oblique, longer, and clothed with extremely dense, short, orange to brownish 

 hairs, resembling the pile on velvet. Engelmanni has variations in punc- 

 tuation, depth of striae and in the stoutness of the third declivital tooth. 

 Ten specimens were dissected, representing all variations, but all were 

 females. The male is thus far unknown. This species is found in the 

 same sticks with tridens, and probably through the wandering of the autumn- 

 feeding adults, even in the same tunnels during the winter. 



The egg-tunnels were not distinguished from those of tridens. 



Host trees. — Picea engelmanni, and probably also P. canadensis. 



Distribution. — Known to us from the Selkirks and Rockies of central 

 British Columbia and from Alberta. 



Ips yohoensis Sw.; Dom. Ent. Br., Dept. Agric, Bull. 14: 31, 1917. 



A species with the pronotal and elytral characters of tridens Mannh., 

 but distinct by the characters of the front. The front is very finely and 

 very densely granulate and finely pubescent on the cephalic half; slightly 

 but distinctly transversely elevated behind the epistoma, which is broadly 

 triangularly impressed medially, immediately in front of the elevation; the 

 epistomal margin and the median impression bearing long yellow hairs; the 

 elevation more evidently pubescent than the remainder of the granulate 

 part of the front, with a trace of a smooth median line. The punctuation 

 of the pronotum is usually coarse and close; the elytral strise are usually 

 deeply impressed and coarsely punctured with sparser interstrial punctures 

 nearly as large as those of the strise. The male has the front somewhat 

 more strongly granulate and the third declivital tooth usually somewhat 

 longer and more evidently capitate. 



Variations in the size of the punctures are found and also in the depth 

 of the striae. The median line on the front is in some individuals smooth, 

 shining, sulcate from the epistomal impression to the vertex, and guarded 

 on each side by a small tubercle at the summit of the epistomal elevation. 

 A considerable number of our specimens have the front entirely or almost 

 entirely free from pubescence. They were taken from the same sticks as 

 the typical series and are probably abraded. 



Host trees. — Picea engelmanni and probably P. canadensis. 



Distribution. — Known to us only from the Yoho valley, British Colum- 

 bia. 



PLATE 28. 



Dendroctonus pseudotsugce Hopk.; Tunnels on the inner face of the bark of Douglas fir; one-half 

 natural size (Author's illustration). 



